* As I mentioned, US data is not very credible because of a data collection fumble.
* There are legitimate concerns of vaccine effectiveness dropping over time: either VE is constant over time, or boosters are necessary, but not both at the same time. Note Israel is at 40% population boosted.
* Recent Canada data is the most promising with VE against Delta infection of 87-92%. The catch is that the measurement stops at 5 months. Perhaps mix & match + large interval between shots is the golden recipe!
* OTOH, UK data is significantly less rosy. Assuming we believe PHE data (VE is negative in 30+yo age group) or the corrected version (VE is <50% in most age groups), something doesn't add up.
May the winter season be light so we can hopefully put the covid crisis past us.
https://www.cbc.ca/news/health/canada-vaccine-effectiveness-...
https://assets.publishing.service.gov.uk/government/uploads/...